Treatment of acetyl cellulose to enhance its elasticity and its power of absorption for dyestuffs.



TATEb A EMIL KNOEVENAGEL, F HEIDELBERG, GERMANY.

TREATMENT OF ACETYL CELLULOSE TO ENHANCE ITS ELASTICITY AND ITS POWER OF ABSORPTION FOR DYESTUFFS.

' senate.

' professor of chemistry,

No Drawing.

To all whom it may concern:

Be it known that I, EMIL KNonvnNAoEL,

a subject of the German lhnperor, residing at Heidelberg, Germany, have invented certain new and useful Improvements in the Treatment of Acetyl Cellulose to Enhance its Elasticity and its Power of Absorption for Dyestuffs, of which the following is a specification.

My application for patent Serial No. 403573, filed'23rd November 1907 describes a process for dyeing acetyl cellulose and filaments and other productsof the same in aqueous solution, which materials may be dyed easily and completely, if the acetylcellulose has been subjected to a preliminary treatment with organic compounds and espeeially with their solutions in water, after r with Water.

which the superfluous liquid is pressed out or the materials are washed with water and then the materials dyed in aqueous solutions in the known manner. Further experiments have shown, that by treating the acetylcellulose with solutions of inorganic acids a modification of the surface may be produced similar to that obtainable by mixtures of organic compounds and their aqueous solutions, which modification shows itself chiefly by a strong swelling or increase of volume. This swelling is accompanied by a large increase of the power of absor tion for dyes in dyeing by known methods. In the same manner the power of absorbing amins and phenols is enhanced, which bodies may then be converted into dyes on the fiber by known methods, or which have already the nature of dyes and whose color may be deepened. on the fiber by known methods. At the same time this treatment of acetylcellulose with solutions of inorganic acids enhances considerably the elasticity of acetyl-eellulose, although it is not possible to prove any appreciable hydrolytic decomposition of the acetyl cellulose treated in this manner, and the same treatment also pro-- duces a bleaching effect. The property of acetyl cellulose, of, being dyed easily, re mains unimpaired after this treatment with solutions of inorganic acids, even if the solutions of inorgamc acids are afterward completely removed by washin for instance In a dry condition, however, the acetyl cellulose, treated as described, re-

Speclflcation of Letters Patent.

Application filed April 30,

Patented Jan. 10, 1911.

1909. Serial No. 493,158.

tains the property of not taking up dyes, unlike ilry cellulose, which as is well known, is dyed by substantive dyestuffs. The acetyl cellulose treated with inorganic acids, has therefore not been saponified by this treatment; The enhanced elasticity of the acetyl cellulose treated as described, is however preserved completely, even after the drying. The acetyl cellulose preferably used in my present process is a triacetyl cellulose. After treatment with inor ani'c acids it is soluble in glacial acetic aci and chloroform, sparingly soluble in acetone and insoluble in ether, carbon-tetra-chlorid and acetylenetetrachlorid.

The followin example will serve to explain the detai sof procedure :-Filaments or films of acetyl cellulose are treated with concentrated aqueous hydrochloric acid preferably of about 37 per cent. strength, or a similarly acting acid of suitable strength, such as a '65 per cent. hydrobromic acid or a 50 MW cent. nitric acid or a 50 per cent. sulfuric acid for about five minutes, thereby causing it to swell or increase in volume. If the acetyl cellulose is subsequently washed with water, it osscsses a high degree of elasticity even after drying. After washing, and'before it has dried, the acetyl cellulose thus treated may be dyed. easily and fully What I claim is 1. In the herein described process of dyeing acetyl cellulose, the preliminary step 0 enhancing the elasticity and power of absorption of acetyl cellulose, which consists in treating the acetyl cellulose with a solution of hydrochloric acid and then removing the superfluous acid.

2. The herein described process for dyeing acetyl cellulose, which consists intreat- Water and then dyein the acetyl cellulose 10 ing thlc uoetyl cellulose with a solution of 111 an aqueous dyc-stufl solution. hydrochloric acid, removing the superfluous In testimony whereof I have hereunto set acid and then dyeing in an aqueous dye-stuff my hand in presence of two subscribing Witsolution. nesses.

3. The herein described process for dye- I EMIL KNOEVENAGEL. ing ucctyl cellulose, which consists in treat- Witnesses: iug the acetyl cellulose with an aqueous so- ALBERT KNOLL,

luliou of hydrochloric acid, rinsing it with HERMANN TAEGER. 

